package ebupt.vpnauth;

import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.KeySpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

import org.apache.commons.codec.binary.Base64;

public class DesEncrypter {

	private Cipher ecipher;
	private Cipher dcipher;

    // 8-byte Salt
	private byte[] salt = {
    		(byte)0x32, (byte)0xA9, (byte)0x56, (byte)0x35,
    		(byte)0x9B, (byte)0xE3, (byte)0xC8, (byte)0x03
    };

    // Iteration count
	private int iterationCount = 23;
	
	public DesEncrypter() {
    	String passPhrase = "mMary has a little Lamb, little 1amb, little lame";
        try {
            // Create the key
            KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount);
            SecretKey key = SecretKeyFactory.getInstance(
                "PBEwithMD5andDES").generateSecret(keySpec);
            ecipher = Cipher.getInstance(key.getAlgorithm());
            dcipher = Cipher.getInstance(key.getAlgorithm());
            // Prepare the parameter to the ciphers
            AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
            // Create the ciphers
            ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
            dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
        } catch(Exception e) {
        }
    }
    
    public String encrypt(String str) {
        try {
            // Encode the string into bytes using utf-8
            byte[] utf8 = str.getBytes("UTF8");
            // Encrypt
            byte[] enc = ecipher.doFinal(utf8);
            // Encode bytes to base64 to get a string
            return new String(Base64.encodeBase64(enc));
        } catch (Exception e) {
        }
        return null;
    }

    public String decrypt(String str) {
        try {
            // Decode base64 to get bytes
            byte[] dec = Base64.decodeBase64(str.getBytes());
            // Decrypt
            byte[] utf8 = dcipher.doFinal(dec);
            // Decode using utf-8
            return new String(utf8, "UTF8");
        } catch (Exception e) {
        }
        return null;
    }

}